The present invention relates to a holding device for a specimen, mainly a wafer, and a charged particle beam device.
A device for treating a semiconductor wafer with a charged particle beam or a device for inspecting a circuit pattern on the semiconductor wafer with the charged particle beam, has a device for holding the semiconductor wafer as a work piece or an object to be inspected.
As an example of such device, an electron beam measuring apparatus is known. It measures width and position of the circuit pattern formed on the semiconductor wafer with the electron beam as the charged particle beam, and has an electron beam probe, an image processor, a specimen stage and so forth. In the electron beam measuring apparatus, an intensity of emitted energy of the electron beam is adjusted by applying a voltage to the semiconductor wafer so that the width and position of the circuit pattern are measured with a desired accuracy and resolving power while preventing an element of the circuit pattern from being damaged by the electron beam. This voltage application is called as retarding. Such technique is disclosed by, for example, JP-A-2-142045 and JP-A-5-258703 (U.S. Pat. No. 5,502,306).
As a method for making an electric field generated over the semiconductor wafer constant to decrease a beam shift, a method in which an electrode is arranged on an outer periphery of the wafer to make the electric field constant, is known. The electrode is an electrically conductive plate having the same height as a surface of the wafer with a small clearance with respect to the wafer. An effect of the electrode for making the electric field constant is described in detail by JP-A-2000-149845.